A major effort to recover the hydrocarbon values from tar sands on a commercial scale was started with the official opening of the great Canadian oil sands plant in 1967. A great deal of research and experimentation preceded this event and research efforts are still continuing. The ultimate objectives of the research have been to improve the quality and quantity of the recovered hydrocarbon products and to improve the environmental acceptance of the overall process.
Processes for recovering oil from carbonaceous material such as oil shale have existed for some time. One such process is described in U.S. Pat. No. 4,340,463 (Harak) issued July 20, 1982. In this patent a system is provided for utilizing fines of carbonaceous materials to obtain the maximum utilization of the energy content of the fines and produce a waste which is relatively inert and of a size to facilitate disposal. The process involves employing a cyclone retort which pyrolyzes the fines in the presence of heated gaseous combustion products. The cyclone retort has a first outlet through which vapors can exit that can be cooled to provide oil and a second outlet through which spent shale fines are removed. A burner connected to the spent shale outlet of the cyclone retort burns the spent shale with air to provide hot combustion products that are carried back to the cyclone retort to supply gaseous combustion products used therein. The burner heats the spent shale to a temperature at which it forms a molten slag and the molten slag is removed from the burner into a quencher that suddenly cools the molten slag to form granules that are relatively inert and of a size that is convenient to handle for disposal in the ground or in industrial processes.
This oil shale process, however, suffers from several drawbacks. First, the gases produced by this process are diluted with combustion products and thus their heating value is much reduced. Second, this process lacks the flexibility necessary for hydrocarbon recovery from tar sands because tar sands of different types will have a broad range of bitumen content. Thus, there is a need for a process which does not dilute the hydrocarbon gases produced with combustion products and which is capable of utilizing tar sands having a broad range of bitumen content.